Aneursym occlusion system and method

ABSTRACT

An aneurysm occlusion system includes a device positionable within a cerebral blood vessel covering a neck of an aneurysm on the blood vessel. The device includes an expandable tubular element having a lumen surrounded by a sidewall including a plurality of gaps. When expanded, the tubular element includes longitudinal standards arrayed helically in a proximal to distal direction. The standards support struts and the gaps are defined between adjacent struts and are sufficiently large to permit delivery of embolic coils or other embolic materials therethrough.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/906,714 (Attorney Docket No. 41507-714.201), filed May 31, 2013, nowU.S. Pat. No. ______, which claims priority to U.S. ProvisionalApplication No. 61/655,116 (Attorney Docket No. 41507-714.101), filedJun. 4, 2012; U.S. patent application Ser. No. 13/906,714 (AttorneyDocket No. 41507-714.201), filed May 31, 2013, now U.S. Pat. No. ______,is a continuation-in-part of U.S. patent application Ser. No. 13/312,816(Attorney Docket No. 41507-713.201), filed Dec. 6, 2011; and is also acontinuation-in-part of U.S. patent application Ser. No. 11/784,236(Attorney Docket No. 41507-705.201), filed Apr. 6, 2007, which claimspriority to U.S. Provisional Application Serial No. 60/790,160 (AttorneyDocket No. 41507-705.101), filed Apr. 7, 2006, the disclosures of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the fields of systems andmethods for treatment of aneurysm, including implanting one or moreintravascular devices for occlusion of the aneurysm.

An aneurysm is an abnormal ballooning of a region of a blood vessel walldue to weakening of the wall tissue. While aneurysms can occur in anyartery of the body, a large percentage of aneurysm are found in thecerebral blood vessels. If left untreated, such aneurysms can rupture,leading to life threatening hemorrhaging in the brain which can resultin death or severe deficit.

Aneurysms that do not rupture can form blood clots which can break awayfrom the aneurysm potentially causing a stroke. In some patients,aneurysm can put pressure on nerves or brain tissue, causing pain,abnormal sensations, and/or seizures.

One current practice for treatment of an aneurysm includes surgicalplacement of an aneurysm clip across the aneurysm to prevent blood flowinto the aneurysm. Naturally, this procedure requires highly invasivebrain surgery and thus carries many risks.

In a less invasive catheter-based technique for aneurysm treatment,filler material is carried through the vasculature to the site of theaneurysm and used to pack the aneurysm. Materials used for this purposeinclude platinum coils and cellulose acetate polymer to fill theaneurysm sac. While these techniques have had some success, questionsremain concerning their long-term effectiveness, ease of use, as well astheir potential for rupturing the aneurysm or triggering clot formation.In addition, there is some risk of post procedure migration of embolicmaterial from the aneurysm into the parent blood vessel.

According to another prior art aneurysm treatment, a mesh or braidedstent-like device is positioned within a blood vessel such that itbridges the aneurysm, blocking flow of blood into the aneurysm. Aproblem encountered with devices of this type is that the sidewalls ofthe devices not only occlude blood flow into the aneurysm, but they willalso block flow between the blood vessel and any side branch vesselsthat the stent happens to cover. See FIG. 1A, which shows a blood vesselV, aneurysm A, and side branch vessel B. In some prior art modificationsto the stent-type devices, the devices include sidewalls that are notocclusive around the full circumference of the device. In implantingthese devices, the physician must make certain that the occlusiveportion of the device's circumference covers the aneurysm and not any ofthe side branch vessels.

Returning to the aneurysm coil embolization solution mentioned above, atypical procedure is illustrated in FIGS. 2A-2D. A typical occlusioncoil is a wire coil having an elongate primary shape with windingscoiled around a longitudinal axis. It is constrained in an elongateconfiguration or primary shape within the catheter for delivery throughthe interior of the catheter. The catheter is introduced into thefemoral artery and navigated through the vascular system underfluoroscopic visualization. The catheter distal end is positioned at thesite of an aneurysm within the vasculature of the brain. (See FIG. 2A,illustrating catheter distal end D as it is being positioned at the siteof aneurysm A.)

With proper positioning of catheter distal end D confirmed, the coil ispassed from the catheter into the aneurysm. The coil reverts to a threedimensional configuration after release from the distal end of thecatheter into the interior of the aneurysm. Once released from thecatheter, the coil assumes a secondary shape selected to optimizefilling of the aneurysm cavity, and the catheter may be withdrawn fromthe vessel. (See FIGS. 2B-2C, illustrating the release of coil C intoaneurysm A.) Multiple coils may be introduced into a single aneurysmcavity for optimal filling of the cavity. The deployed coils serve toblock blood flow into the aneurysm and reinforce the aneurysm againstrupture. The implants are intended to embolize the blood inside theaneurysm in order to diminish additional blood flow into the aneurysm.Eventually the embolization completely closes the aneurysm to furtherflow of blood into the aneurysm. For a more detailed description ofembolic coils and related methods, see commonly owned U.S. patentapplication Ser. No. 12/498,752 and Ser. No. 12/695,035.

In some cases, there is a significant risk of migration of the coils orother implants out of the aneurysm and into the parent vessel afterdelivery and deployment (or release or detachment) of the coils. This isespecially a risk in the case of a “wide neck” aneurysm. (See FIG. 2D).Migration of a coil or coils into the circulatory system is undesirableand can lead to occlusion of the parent vessel, other vessels, as wellas lead to other unintended effects.

In such cases, it may be desirable to “bridge” the neck of the aneurysmwith a device prior to the delivery of embolic implants. Such a bridgedevice may be a generally tubular structure that is positionable viacatheter within the parent vessel, covering the neck of the aneurysm.Positioning of such a device is typically performed with the assistanceof a guidewire and fluoroscopic visualization. The generally tubularaneurysm bridge is deployed across the neck of the aneurysm and allowedto expand into contact with the vessel walls. Embolic coils are thendelivered into the aneurysm through voids in the “walls” of the tubularbridge.

Shortcomings of prior art attempts to bridge the neck of an aneurysmprior to embolic coil delivery include difficulties with tracking anddeployment of the device, problems resheathing and repositioning thedevice, entanglement between the coil delivery catheter and the bridgedevice, and problems with portions of the device “bulging” into theaneurysm. Therefore, there remains a need for smooth, kink-freetracking, deployment, repositioning, and reliable, uniform deployment.There also remains a need for a sufficiently flexible device havingadequate column strength.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an aneurysm in a blood vessel and thecorresponding blood flow.

FIG. 2A-2D illustrate some of the steps of a method of implanting one ormore embolic coils into an aneurysm in a blood vessel.

FIGS. 3A-3E illustrate some of the steps of a method of implanting adevice to bridge the neck of an aneurysm and then implanting one or moreembolic coils into the aneurysm.

FIG. 4A-4G illustrate some of the steps of an alternative method ofimplanting a device to bridge the neck of an aneurysm and thenimplanting one or more embolic coils into the aneurysm.

FIG. 5 is a perspective view of a finished device according to theinvention, in a deployed configuration that results when the device isnot placed in a vessel prior to deployment, hereinafter referred to as a“deployed in air”.

FIG. 6 illustrates a side view of a device according to the inventiondeployed within a curved, transparent model vessel.

FIG. 7 illustrates a truncated side elevational view of a deviceaccording to the invention in a deployed in air configuration.

FIGS. 7A-7C are cross-sectional end views of the embodiment of FIG. 7taken along section lines A, B, and C.

FIG. 8 is a perspective proximal end view of a finished device accordingto the invention in a deployed in air configuration.

FIG. 9 is a plan view of a cut pattern for manufacture of a deviceaccording to the invention. Although devices according to the inventionare preferably cut from tubular structures, twisted and shape set, FIG.8 illustrates the cut tube as though it were longitudinally cut andflattened into a sheet before twisting, so that the pattern features maybe more easily viewed.

FIG. 10 is a plan view of a cut pattern of an alternative embodimentaccording to the invention. Although the bridge devices are preferablytubular structures, cut from a tube, twisted and shape set, FIG. 9illustrates the device as though it were longitudinally cut andflattened into a sheet before it is twisted, so that its features may bemore easily viewed.

FIG. 11 is a truncated plan view of an embodiment according to theinvention. Although the bridge devices are preferably tubularstructures, FIG. 11 illustrates the device as though, after shapesetting to include a right hand twist, it were longitudinally cut andunrolled so that its features are more easily viewed.

FIGS. 11A-11B are enlarged views of Details A and B of FIG. 10.

FIG. 12 is a side elevation, partial cross sectional view of the distalend of a pusher catheter according to the invention, shown within avessel and with the proximal end an aneurysm bridge device according tothe invention mounted thereon.

FIG. 13 is a perspective view of a pusher tip according to theinvention.

FIG. 14 is a perspective view of an alternative embodiment of the pushertip of FIG. 11.

DETAILED DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure. The aneurysm occlusion system disclosed herein boasts avariety of inventive features and components that warrant patentprotection, both individually and in combination.

In FIG. 3A, a system for bridging the neck of an aneurysm beforedelivering embolics to the aneurysm is illustrated during a step of amethod according to the invention. (An alternative exemplary method isdiscussed below in relation to a description of FIGS. 4A-4G.) FIG. 3Aillustrates a system after the step of positioning the system in avessel V having aneurysm A. The aneurysm bridge device and accompanyingdelivery system include aneurysm bridge device 1, sheath 2 and pusher 5.A guide wire (not pictured) may also be utilized in the step ofpositioning the system in a vessel. Aneurysm bridge device is agenerally tubular device capable of being retained in a reduced profiledelivery configuration. The aneurysm bridge device 1 is proportioned tobe implanted within the cerebral vasculature including, but not limitedto, the Internal Carotid Artery, External Carotid Artery, VertebralArtery, Basilar Artery, Middle Cerebral Artery, Anterior CerebralArtery, and the Posterior Cerebral Artery.

Generally speaking, aneurysm bridge device 1 is a tubular device havingcentral lumen 6. It is retained in a reduced profile deliveryconfiguration by sheath 2, and it is capable of expanding into contactwith the vessel walls when released or deployed to a larger diameterconfiguration. Preferred devices 1 are expandable to an outer diameterin the range of 2.0 mm-6.0 mm. The user may be provided with a set ofmultiple aneurysm bridge devices of different diameters and differentlengths so that the device with the most appropriate dimensions may bechosen for the procedure.

Suitable materials for device 1 include shape memory materials includingsuperelastic Nitinol or shape memory polymers, or other materials suchas stainless steel, composite materials, or combinations of metals andpolymeric materials. In a preferred embodiment, the aneurysm bridgedevice 1 may be formed by laser cutting features into a length ofsuperelastic Nitinol tubing, then chemically processing andshape-setting the material one or more time using methods known to thoseskilled in the art. The device may then be chilled to below its shapememory transition temperature and loaded onto pusher 5 and retained bysheath 2.

In the example of a method according to the invention illustratedbeginning in FIG. 3A, proximal end 3 of aneurysm bridge device 1 isdisposed upon the distal end 4 of pusher 5 while being retained bysheath 2. Sheath 2 is an elongate tubular catheter preferably formed ofa polymeric material such as Pebax nylon, urethane, PTFE, Polyimide,metals such as Stainless Steel, Platinum, etc., or other suitablematerial. A central lumen extends the length of sheath 2. The sheath isproportioned for passage through cerebral vasculature, and may have anouter diameter in the range of 1 mm-3 mm.

Pusher 5 is an elongate tubular member having optional lumen 7. Thepusher may be formed of suitable polymers, metals, and/or compositematerials. Distal end or tip 4 of pusher 5, which is described ingreater detail below in a description of FIGS. 11-14, includes apertures8. When loaded onto distal tip 4, device 1 is threaded over pusher 5,and positioned so that bumps 9 of its proximal end 3 are aligned with,or inserted into, apertures 8. Bumps 9 may alternatively be projections,tabs, posts, clips, or any structures, preferably male, that aresuitable for engaging apertures 8. Similarly, apertures 8 mayalternatively be pockets, holes, hollows, grooves, or any structures,preferably female, for receiving bumps 9. Sheath 2 retains bumps 9 inengagement with apertures 8 as it retains aneurysm bridge device 1 in areduced profile configuration. Device 1 remains in the reduced profileconfiguration during tracking of the device under fluoroscopicvisualization to a treatment site within the vasculature of a subject.

After positioning aneurysm bridge 1 across the opening of aneurysm A,the device is then deployed and either temporarily or permanentlyimplanted in the vessel. As illustrated beginning with FIGS. 3B, inorder to deploy aneurysm bridge 1, sheath 2 is withdrawn proximally topermit the device 1 to expand to its unconstrained configuration intocontact with the inner walls of the parent vessel V. When sheath 2 iscompletely withdrawn from the length of bridge device 1, device 1expands to a deployed diameter, as illustrated in FIG. 3C. Also, whensheath 2 is withdrawn from along the length of device 1, bumps 9 are nolonger retained in apertures 8. Pusher 5 may then be withdrawn from thevessel V. Alternatively, pusher 5 may be left positioned in vessel V,and central lumen 7 may be utilized as a conduit or passage in asubsequent step. Further, if the user wishes to reposition device 1,sheath 2 can be advanced distally in order to resheath device 1. Thesteps of positioning and deploying device 1 described above can then berepeated.

Voids in the walls of the tubular device 1 permit the catheter-baseddelivery of embolic coils through the walls and into the aneurysm.(Alternatively, embolic coils may be implanted according to a method inwhich the coils are not delivered through the voids in the wall ofdevice 1, as described in greater detail below.) As illustrated in FIG.3D, delivery catheter D may be positioned within vessel V (and/oralternatively within pusher lumen 7). Embolics including one or moreembolic coils may then be delivered to the aneurysm, in much the samemanner as described above in relation to FIGS. 2A-2C, except that theyare delivered through the voids in the “walls” of the bridge 1. Theposition of the device 1 across the neck of the aneurysm prevents theunintended escape of embolic materials out of the aneurysm and into theparent vessel following the conclusion of the procedure (See FIG. 3E).The device remains in place in the parent vessel across the aneurysmneck during the delivery of coils, thereafter, and if desired,permanently.

Turning now to an alternative method according to the invention, FIGS.4A-4G illustrate exemplary steps according to the alternative method. Inthe steps illustrated in FIGS. 4A-4G, the aneurysm bridge 1 describedabove in relation to FIGS. 3A-3E is again utilized, but according to asomewhat different method than that described in the foregoingparagraphs. FIG. 4A illustrates an early step according to the inventionfollowing the introduction of delivery catheter D into a vessel V havinganeurysm A. One or more embolic coils, in the elongate configuration, isconstrained by and carried within delivery catheter D. The distal end ofdelivery catheter D is positioned proximate aneurysm A.

Following positioning of delivery catheter D proximate aneurysm A, theaneurysm bridge device 1 and accompanying delivery system are introducedinto the vessel V and positioned proximate aneurysm A, generally asillustrated in FIG. 4B. In addition to aneurysm bridge device 1, thedelivery system includes sheath 2 that was illustrated and discussedabove. Sheath 2 retains aneurysm bridge device 1 in a reduced profiledconfiguration. Device 1 is capable of expanding into contact with thevessel walls, or released or deployed to a larger diameterconfiguration, when sheath 2 is withdrawn.

There are many similarities between the delivery system illustrated inFIG. 3B and FIG. 4B. However, the system illustrated in FIG. 4B includesalternative pusher 14. Pusher 14 may be formed of suitable polymers,metals, and/or composite materials. Pusher 14 may include any of thematerials and dimensions of pusher 5 described above, but pusher 14 doesnot include a central lumen. A guide wire (not pictured) may also beutilized in the step of positioning the system in a vessel.

Prior to introduction into vessel V, the proximal end 3 of aneurysmbridge device 1 is disposed upon the distal end of pusher 14. Exemplarydistal tips of pusher 14 are described in greater detail below in adescription of FIGS. 11-14. Distal tip 4 again includes apertures 8.When loaded onto distal tip 4, device 1 is threaded over pusher 14, andpositioned so that bumps 9 of its proximal end 3 are aligned with, orinserted into, apertures 8. Bumps 9 may alternatively be projections,tabs, posts, clips, or any structures, preferably male, that aresuitable for engaging apertures 8. Similarly, apertures 8 mayalternatively be pockets, holes, hollows, grooves, or any structures,preferably female, for receiving bumps 9. Sheath 2 retains bumps 9 inengagement with apertures 8 as it retains aneurysm bridge device 1 in areduced profile configuration. Device 1 remains in the reduced profileconfiguration during tracking of the device under fluoroscopicvisualization to a treatment site within the vasculature of a subject.

After positioning aneurysm bridge 1 across the opening of aneurysm A,and proximate the distal end of delivery catheter D, the device is thendeployed. As illustrated beginning with FIGS. 4C, in order to deployaneurysm bridge 1, sheath 2 is withdrawn proximally to permit the device1 to expand to its unconstrained configuration into contact with theinner walls of the parent vessel V. When sheath 2 is completelywithdrawn from the length of bridge device 1, device 1 expands to adeployed diameter, as illustrated in FIG. 4D. If the user wishes toreposition device 1, sheath 2 can be advanced distally in order toresheath device 1. The steps of positioning and deploying device 1described above can then be repeated. Pusher 5 may then be eitherwithdrawn from the vessel V or may be left positioned in vessel V. Asillustrated in FIGS. 4C and 4D, delivery catheter D remains in placeproximate the aneurysm during the steps of the method described herein.

As illustrated in FIG. 4E-4F, one or more embolic coils (or otherembolic material) may then be delivered to the aneurysm, in much thesame manner as described above, except that they are delivered directlyinto the aneurysm, instead of through the voids in the “walls” of thebridge 1. The position of the device 1 across the neck of the aneurysmprevents the unintended escape of embolic materials out of the aneurysmand into the parent vessel following the conclusion of the procedure(See FIG. 4G). The device remains in place in the parent vessel acrossthe aneurysm neck during the delivery of coils, thereafter, and ifdesired, permanently.

Details of an aneurysm bridge device according to the invention areillustrated in FIG. 5. Aneurysm bridge 10 is illustrated in a deployed“in air” configuration. Aneurysm bridge 10 is a more or less tubulardevice capable of being retained in a constrained form or shape prior todeployment, and then expanded (or permitted to expand) into contact withthe walls of a vessel when deployed. Consequently, it may be positionedand delivered using a variety of methods similar to those summarizedabove in conjunction with the description of FIGS. 3A-4G. As describedin detail below, aneurysm bridge 10 has many advantages over prior artdevices for improved delivery, deployment, retraction, repositioning,and redeployment .

Aneurysm bridge 10 may be constructed from any number of compositionshaving suitable biocompatibility and strength characteristics. In theembodiment illustrated in FIG. 5, aneurysm bridge 10 is constructed fromNitinol® with “shape memory” or superelastic characteristics to optimizeself expansion of the device upon deployment. Aneurysm bridge 10 isconstructed by cutting features into a Nitinol tube. For example, a tubeof 3.5 mm outer diameter and 0.005 inch thickness may be cut in apredetermined pattern of bands, struts, and/or connectors. Examples ofsuitable patterns are illustrated below in FIGS. 9 and 10, thoughvariations on the patterns are within the scope of the invention. Afterthe features are cut into the tube, the tube is twisted and shape set.It has been found that a helical arrangement resulting from the twisthelps the deployed device conform to the vessel walls, and it alsoimproves the ability of the device to resist kinking.

An aneurysm bridge according to the invention may be dimensioned in anynumber of suitable sizes and lengths, depending upon the location of theaneurysm, variances in patient anatomy, and the size and shape of theaneurysm. Aneurysm bridge 10 of FIG. 5 in its expanded configuration isapproximately 2.0-6.0 mm at its maximum outer diameter, and between10-45 mm in length. Aneurysm bridge 10 can be described while viewingFIG. 5 from left to right, with its proximal end 15 on the left side ofthe figure, its distal end 18 on the right, and a central region 11disposed therebetween. As described in greater detail below inconjunction with a description of FIGS. 7-7C, generally tubular aneurysmbridge 10 has a generally ovular shaped cross section at its proximalend 15 and its distal end 18 when it is deployed in air. It is howevergenerally circular in cross section throughout most of its centralregion 11. When bridge 10 is deployed in a vessel, it generally takesthe shape and cross section of the vessel.

In FIG. 5, two standards 20 and 22 can be seen extending in a helicalfashion from proximal end 15 to distal end 18, more or less the entirelength of tubular element 10, though alternative embodiments may have agreater number of standards. The helical array of aneurysm bridge 10 maybe imparted to a cut tube by grasping standards 20 and 22 and applying acircumferential twist. (The extent of circumferential twist can becharacterized in terms of the resulting angle of standards 20 and 22 tothe longitudinal axis of device 10, and is illustrated in FIG. 7 below).Standards 20 and 22 have a width in the range of 0.0020-0.0050 inch,preferably between 0.0030-0.0045 inch, and impart axial and columnarstrength upon aneurysm bridge 10. The standards may also be used toprovide axial force to the device if it is necessary to reposition thedevice after partial deployment within the vessel as discussed above.Standards 20 and 22 may further be equipped with features to facilitateloading of the finished device 10 into a sheath.

Standard 22 defines a portion of first helical spine 25. First helicalspine 25 extends in a helical fashion along the length of aneurysmbridge 10 from proximal end 15 to distal end 18 as a result of thecircumferential twist applied to standards 20 and 22. Similarly,standard 22 defines a portion of second helical spine 27. Second helicalspine 27 extends in a helical fashion from proximal end 15 to distal end18 of aneurysm bridge 10. First helical spine 25 and second helicalspine 27 impart columnar strength and uniform, reduced size gap spacingalong the length of the device 10. The specific features that definefirst helical spine 25 and second helical spine 27 will be described indetail in relation to FIGS. 8 and 9, in which the features are moreeasily viewed.

Among the advantages of the invention herein are its superior,kink-resistant, reversible trackability and reversible deployabilitywithin tortuous vasculature. In order to illustrate the superiortracking and reliable deployment of the system, device 10 is showndeployed within a transparent vessel model 30 in FIG. 6. Transparentmodel vessel 30 has a curved configuration and model aneurysm 34 locatedon the “outer” side of curve 36. Device 10 was tracked through curve 36and across the neck of aneurysm 34. Aneurysm bridge 10 was permitted toexpand radially outwardly to closely meet the walls of the vessel model.And despite the curved configuration of the vessel model, aneurysmbridge device readily deploys to contact the walls of the lumen.Moreover, when deployed in a curved vessel, the features of device 10,(which are described more specifically below in conjunction with adiscussion of FIG. 9) are disposed in a uniform, orderly configuration.No portion of aneurysm bridge device 10 bulges or protrudes intoaneurysm 34. Consequently, aneurysm bridge device 10 can be repositionedand redeployed readily if needed, or withdrawn completely from thevessel. And aneurysm bridge device 10 provides orderly gaps betweenstruts or bands through which occlusion coils (not pictured) may be bothdelivered to aneurysm 34 and prevented from escape therefrom.

FIG. 7 illustrates other aspects of aneurysm bridge 10 from a truncatedside elevational view. Firstly, the twist angle mentioned above inrelation to FIG. 5 is more easily viewed in FIG. 7. Twist angle a isillustrated as the angle between standard 20 and longitudinal axis x ofdevice 10. Twist angle a is between 15° and 40°, and preferably between20° and 35°, in either a clockwise or a counterclockwise direction. Aparticular twist angle may be imparted on device 10 after patternfeatures illustrated in FIGS. 9 and 10 below are cut into a Nitinoltube.

FIGS. 7A-7C illustrate cross sectional shapes of device 10 (when it isdeployed in air), along lines A, B and C of FIG. 7 above. FIG. 7Aillustrates the cross section of proximal end 15 at Detail A. Atproximal end 15 of aneurysm bridge 10, standard 20 is generally oppositestandard 22. FIG. 7B illustrates the cross section of central region 11at Detail B. And FIG. 7C illustrates the cross section of aneurysmbridge 10 at detail C. At distal end 18, standards 20 and 22 intersectone another along a wall of aneurysm bridge 10. Apexes 24 are disposedopposite one another, at the narrowest portions of the oval. Centrallumen 28, which extends the length of tubular element 10, isconsequently ovular in cross section at the proximal and distal ends ofaneurysm bridge 10, and circular in cross section in the central regionof the device.

FIG. 8 illustrates aneurysm bridge 10 from a perspective view ofproximal end 15, revealing central lumen 28. (For clarity, the portionof bridge 10 on the “back side” of lumen 28 is illustrated merely bydotted helical lines.) Distal end 18 is essentially facing away from theviewer in FIG. 8. Bridge 10 is again shown deployed in air, and proximalend 15 has a generally ovular cross section. At proximal end 15, theproximal-most ends of standards 20 and 22 lie essentially opposite oneanother, along the narrowest portions of the oval.

FIG. 9 illustrates an example of a cut pattern used to make a deviceaccording to the invention. Although an aneurysm bridge according to theinvention is a generally tubular device shape set into a twistedconfiguration, FIG. 9 illustrates the device as though, before beingshape set into a twist, it has been cut along its length and laid flatso that its features may be more easily viewed. Cut pattern 50 has aproximal end 52 and a distal end 53. Cut pattern 50 also has standards55 and 57. Standard 55 and standard 57 have a similar set of featuresarrayed in a repeating pattern. For ease of reference, these featureswill be described especially in relation to standard 55, though standard57 is also oriented to bands, struts or connectors having generally thesame features. Extending laterally or diagonally from standard 55 is aplurality of bands 60. Bands 60 have strut widths in the range of0.00050-0.00150 inch, and preferably between 0.00060-0.00120 inch. Bands60 in turn extend to define S-connectors 65. Standard 55, bands 60 andS-connectors 65 define a first spine 68. Second spine 69 is defined bythe corresponding features in conjunction with standard 57. In the cutpattern 50, spines 68 and 69 are generally straight. In a finisheddevice, however, a circumferential twist will be shape set into thedevice, placing spines 68 and 69 in a helical configuration.

Connected to the other ends of S-connectors 65 are bands referred to asV-struts 70. Each V-strut 70 includes a short leg 71, a long leg 72, andan apex 73 therebetween. Apexes 73 are disposed pointing toward distalend 53. Though other geometries are possible within the scope of theinvention, the resulting lattice of first spine 68, V-struts 70, secondspine 69 and V-struts 74 will define the skeletal “walls” of thegenerally tubular aneurysm bridge and the shape and size of voids withinthe walls.

The function of S-connectors 65 can be described as limiting theexpansion between bands 60. The expansion limiting function can mosteasily be viewed in FIG. 6. Aneurysm bridge 10, deployed in curved modelvessel 30, has bands 12 and S-connectors 13. The tighter spacing betweenbands 12 is illustrated in comparison to the wider spacing of V-struts19. S-connectors 13 tighten the gaps in the walls of the device,effectively reducing the size of gaps 26 by roughly half, therebyproviding a barrier to coils that may be implanted into aneurysm 34.S-connectors 13 also prevent bands 12 and V-struts 19 from “poking” orprotruding into aneurysm 34, an important advantage if the device mustbe repositioned, especially when the aneurysm is disposed in a curvedvessel, as in the example of FIG. 6. The closely spaced and generallyuniform array imparted by S-connectors 13 is imparted along the lengthof first helical spine 25 (and second helical spine 27, which is notvisible in FIG. 5), and consequently along the length of aneurysm bridge10.

The function of V-struts 19 can be characterized as maximizing theflexibility of the device 10. The flexibility imparted by V-struts 19 isvery important for accommodating the flexure of the device both prior todeployment and over the life of the device. Prior to deployment of thedevice, most of the stress imparted on the device occurs during crimpingdown and loading the device into a sheath, and then tracking the crimpeddevice through tortuous vasculature while crimped down and sheathed.Following deployment of the device within the vessel, most of the stressimparted on the device is a result of the ongoing, long term expansionand contraction due to pulsation of the vessel. In both configurations,the majority of the stress on the device is absorbed by the V-struts 19.It is desirable for the device to be able to flex at the “V”; otherwisethe stress may break the device, or deform the device beyond its abilityto recover, or otherwise cause the device to fail.

The specific structures of bands 12, S-connectors 13 and V-struts 19 ofFIGS. 5-8 are similar to the corresponding features of FIGS. 9 and 10,but can be most easily viewed in FIG. 10. FIG. 10 illustrates analternative embodiment according to the invention. Similar to FIG. 9, itillustrates a cut pattern of a generally tubular device as though itwere cut along the length of the tube before the tube has been shapeset, and laid flat so that the features of the pattern may be moreeasily viewed. Cut pattern 90 has proximal end 92, distal end 93, andstandards 95 and 97. Cut pattern 90 has a lesser number of bands 100than does cut pattern 50 described above. Cut pattern 90 has acorrespondingly fewer number of S-connectors 105 and V-struts 110. Cutpattern 90 accordingly will form a shorter length device than cutpattern 50.

An important similarity between the embodiment of FIG. 10 and otherembodiments is that S-connectors 105 perform the same gap-limitingfunction without sacrificing needed flexibility. In order to performthis function, S-connectors 105 are disposed between bands 100 andV-struts 110, and specifically very near apexes 112 of V-struts 110.V-struts 110 consequently have a short leg 114 and a long leg 116.S-connectors 110 thereby maintain close spacing between bands 100, whilepermitting flexure of apexes 112. Because most of the stress duringflexure of the device made from cut pattern 90 is absorbed by apexes112, it is important that the S-connector not completely prevent flexureof apexes 112. The positioning of S-connectors illustrated in FIG. 9help define first spine 94 and second spine 96, yet permit flexure ofV-struts 110. Apexes 112 additionally point in the direction of distalend 93, facilitating resheathing of the device if needed.

FIG. 11 illustrates a truncated view of a cut pattern to which a righthand twist has been applied. Cut pattern 130 is illustrated as though atwisted tubular aneurysm bridge according to the invention were cutalong its axis and unrolled to better display its features. More easilyviewed in FIG. 11A, Detail A, taken from a distal portion of cut pattern130 of FIG. 11, reveals the structure of bands 150, S-connectors 155,and V-struts 160. Also visible in FIG. 11A is marker 165, which isdisposed on the distal end of standard 170. The distal extension 175 ofstandard 170 is between 0.0200-0.110 inch, and preferably between 0.0300and 0.1050 inch in length.

FIG. 11B is an enlarged view of Detail B, taken from a proximal regionof FIG. 11, to better illustrate some of its features. AgainS-connectors 155 are visible, as are V-struts 160, and standard 170.Affixed near the proximal end of standard 170 is bump 180 (shown from atop view of bump 180). As mentioned above, bump 180 is useful in loadinga finished device on the distal end of a pusher prior to retaining thedevice with a sheath (see FIGS. 3A-3C).

See also FIG. 12, showing an enlarged schematic illustration of a device200 according to the invention mounted on a pusher and retained by asheath. Proximal end 201 of aneurysm bridge 200 is shown mounted on thedistal end of a pusher 202. Bumps 205 are seen in engagement withapertures 210. Sheath 215 retains aneurysm bridge 200 in its reducedprofile delivery configuration, and consequently keeps bumps 205 inengagement with apertures 210 until either proximal withdrawal of sheath215, or until pusher 202 pushes the device out of the end of sheath 215.

FIG. 13 is a perspective view of a pusher tip 300 that is not affixed tothe distal end of a pusher. Pusher tip 300 has a central lumen 305, andthree apertures 310. A greater or lesser number of apertures are withinthe scope of the invention. Similar to the apertures described inrelation to FIGS. 10-11 above, apertures 310 permit the engagement ofbumps on the proximal end of an aneurysm bridge device. Legs 315 andeyelets 317 permit the attachment of pusher tip 300 onto the distal endof a pusher.

FIG. 13 is a perspective view of an alternative embodiment of a pushertip according to the invention. Pusher tip 400 has central lumen 405 andtwo apertures 410 which can accommodate bumps on the proximal end of ananeurysm bridge device, to enhance retention of the device on the distalend of a pusher until deployment of the device at a desired time. Legs415 and eyelets 417 enhance attachment of pusher tip 400 on the distalend of a pusher.

It should be recognized that a number of variations of theabove-identified embodiments will be obvious to one of ordinary skill inthe art in view of the foregoing description. Accordingly, the inventionis not to be limited to those specific embodiments and methods of thepresent invention illustrated and described herein. Rather, the scope ofthe invention is to be defined by the claims and their equivalents.

What is claimed is:
 1. A system for treatment of intracranial aneurysmcomprising: a device for bridging the neck of an aneurysm of a cerebralvessel, said device comprising a tubular element including a pluralityof standards, a plurality of bands connected to the standards, alongitudinal axis, a reduced-profile delivery configuration and adeployed configuration, wherein said standards are oriented at an angleto said longitudinal axis when said tubular element is in said deployedconfiguration so that the standards and the bands together define aplurality of helical spines; an introducer for introducing said tubularelement into a vessel; and a delivery device for delivering embolicmaterial into the aneurysm.
 2. The system according to claim 1 whereinsaid angle is between 15° and 45°.
 3. The system of claim 1 wherein thebands further comprise one or more V-struts, wherein each V-strutcomprises a first leg, a second leg that is longer than said first leg,and an apex between said legs.
 4. The system of claim 1 wherein saidstandards comprise a width of between 0.0020 inch and 0.0050 inch. 5.The system of claim 1 wherein said bands further comprise one or moreV-struts, wherein each V-strut comprises a first leg, a second leg, andan apex between said legs, said first leg further comprising an S-shapedconnector disposed near, but not on, said apex.
 6. The system of claim 1wherein said tubular element comprises shape memory material and saidsystem further comprises a sheath, whereby said tubular element isretained in said low profile delivery configuration, wherein withdrawalof said sheath permits said tubular element to convert to its deployedconfiguration.
 7. The system of claim 6 wherein said tubular element canbe returned to its delivery configuration within said sheath.
 8. Thesystem of claim 1 wherein said system further comprises a sheath, andsaid tubular element can be withdrawn into said sheath via saidintroducer.
 9. The system of claim 1 the introducer further comprising atip comprising a central lumen, one or more legs, and at least oneaperture.
 10. The system according to claim 9 wherein said first andsecond standards further comprises at least one bump configured toengage the at least one aperture.
 11. A method of manufacture of anintravascular device, said method comprising the steps of: providing atube comprising one or more shape memory materials, a longitudinal axis,a proximal end and a distal end; cutting the tube according to apredetermined pattern, wherein the predetermined pattern defines atleast two parallel elongate standards, bands, and gaps between saidbands; applying a circumferential twist to the cut tube to orient theelongate elements at an angle to said longitudinal axis; and applying ashape memory set to the twisted cut tube.
 12. The method according toclaim 11 wherein said shape memory material is nitinol.
 13. The methodaccording to claim 11 wherein said predetermined pattern defines onlytwo parallel elongate standards.
 14. The method according to claim 11wherein said predetermined pattern further defines a plurality ofV-shaped bands having at least one end connected to an elongatestandard.
 15. The method according to claim 14 wherein said V-shapedbands comprise apexes and S-shaped connectors, wherein said S-connectorsare disposed near, but not upon, said apexes.
 16. The method accordingto claim 11 wherein the step of applying a circumferential twist to thecut tube is performed so that at least one of the elongate standardscrisscrosses a second elongate standard at the distal end.
 17. Themethod according to claim 11 wherein said angle is between 15° and 45°.18. A method of treating an aneurysm located in a blood vessel of asubject, the method comprising the steps of: introducing an elongatetubular delivery device into the blood vessel and proximate theaneurysm, the delivery device suitable for delivery of embolic material;introducing a tubular element for bridging the neck of the aneurysm, thetubular element being radially expandable from a compressed position toan expanded position, having a proximal end, a distal end, alongitudinal axis, at least two elongate standards and a plurality ofbands attached thereto, the bands having gaps therebetween and furthercomprising a first leg, a second leg that is longer than said first leg,and an apex between said first leg and said second leg, the elongatestandards arranged helically about the longitudinal axis from theproximal end to the distal end when the tubular element is in theexpanded position, the elongate standards and bands together forming afirst helical spine and a second helical spine; bridging a neck of theaneurysm with the tubular element; permitting the expandable tubularelement to expand; delivering one or more embolic materials to theaneurysm; and withdrawing the tubular delivery device.